1. What is the link to the documentation section that needs improving?

https://python-oracledb.readthedocs.io/en/latest/user_guide/troubleshooting.html#dpy-4011

2. Describe the confusion

This error says the only cause is having NNE enabled (and thus requiring the thick client), but it can also occur under the following circumstances:

• The Oracle server supports TLS and NNE and is running in a Docker container or otherwise on a platform/behind a firewall that does not support out-of-band break messages
  • NNE support may not be required, all I know for sure is that my environment has both TLS and NNE support
• The server's sqlnet.ora file has DISABLE_OOB_AUTO=TRUE (so no OOB test is performed upon client connect which would return ORA-12637), but does not set DISABLE_OOB=on to disable OOB altogether (so it's still possible for clients to attempt it)
• The client connects and seems to work fine until it does something that causes an out-of-band message to be sent, resulting in the connection failing and DPY-4011 appearing in the logs

3. Suggest changes that would help

Mention that DPY-4011 can also occur, even for established TLS connections, if OOB messaging is attempted in an environment that lacks OOB support (such as Docker) but whose Oracle server has not fully disabled it.

The server-side solution would be to set DISABLE_OOB in the sqlnet.ora file, but setting the disable_oob=True connection option can also mitigate it on the client side.